Barr is a generalization of a variety of drugs manufactured by Barr Pharmaceuticals. This particularly pertains to prescription strength cough syrups containing the narcotics codeine or hydrocodone. This is often misspelled as "barre"

adj., a person or an object that is very awkward or unusual in their current state or environment; a state of existence in which a person seems incapable of blending in conspicuously or acting in such a way so as to appear normal; existing in a perpetual state of being "lame"

From the critically acclaimed movie 'Team America: World Police' we have yet another word of Engrish origin that has revolutionized the way we speak in this day and age. Barrs is the Engrish pronounciation of the English word balls.

barr is a word used in conjunction with the recreational or medicinal use of marijuana.
I have heard it mainly in the York area and it was derived from the word battered, which when said fast and lazily becomes the word barr. It has since then evolved to mean many things: